textproduct: Rapid City

KEY MESSAGES

-Widespread showers and a few thunderstorms will continue through tonight before gradually ending Thursday into Thursday night

-Total rainfall amounts of one quarter inch to two inches are expected, with the highest amounts across western and central SD

-Dry and warmer weather this weekend and most of next week

DISCUSSION

(This Evening Through Wednesday) Issued at 152 PM MDT Wed Sep 17 2025

Radar imagery this afternoon shows widespread rain and a few embedded thunderstorms across western South Dakota, with more scattered showers into northeast Wyoming. This activity is associated with an upper level low centered near KVTN, and a deepening 1016mb surface low near Draper. The widespread rain will continue to wrap around the low into this evening before gradually shifting eastward overnight into Thursday as the surface low moves off to the east per 12Z guidance. Rain chances near 100 percent today across western SD will subsequently diminish down to just slight/low chances by Thursday afternoon before ending across the cwa by Thursday night into early Friday. Latest QPF totals for this event indicate around one half inch or less of rainfall across northeast Wyoming, with one half inch along the WY/SD border to near 2 inches along the eastern cwa border. No flooding impacts are anticipated due to the long duration of this beneficial light to moderate rain event. Of note, north to northeast winds are anticipated to increase considerably late today into tonight over the western and central SD plains as the surface low deepens to around 1011mb per CAMs, creating a 5-6mb pressure gradient between KRAP and KICR. This should allow for occasional north to northeast wind gusts reaching the 30-40 mph range in our eastern half tonight before subsiding Thursday morning.

The upper low will linger across SD through Friday before finally getting kicked off to the east as a stronger H5 shortwave shifts southeast out of southern Canada by Saturday. Dry northwest flow will bring a dry and warmer weekend for the region with highs warming back into the 70s and 80s for Saturday and Sunday. The forecast for next week is now more uncertain as the 12Z GFS/ECMWF show yet another upper low taking shape across the northern Rockies and moving into the northern Plains early next week, which could potentially bring more rain and thunderstorms to the forecast area Monday and Tuesday. Due to the uncertainty in the overall pattern and the previously dry forecasts, precip chances will remain low to negligible for early next week, but may need to be bumped up in the coming days. Regardless, the long range pattern continues to look quite active for the northern Plains as a large upper trough takes hold over the western CONUS.

AVIATION

(For the 06Z TAFS Through 06Z Thursday Night) Issued At 1123 PM MDT Wed Sep 17 2025

MVFR/IFR conditions with rain will continue overnight into Thursday, especially across western SD. Conditions will gradually improving to VFR from west to east over the next 24 hours...first across NE WY tonight, then western SD through the day Thursday.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.